1. Field of the Invention
The present invention relates to a module made of one or more semiconductor sensors, such as a temperature sensor, a tire pressure sensor, an acceleration sensor, a rotation speed sensor, a steering angle sensor, etc., in a flexible housing as it can, among other things, be vulcanized into rubber tires.
2. Description of the Related Art
In order to increase the operational safety of vehicles of all kinds, the development of technical assemblies for monitoring most varied properties of the wheels and tires has been worked on for a long time. In this context, properties to be monitored can be the temperature, the internal pressure, the deformation, the acceleration, the tilt angle etc. of the wheels or tires. Changes on the wheels and tires caused by the usage and wear are to be recognized to avoid accidents or at least minimize the risk of accidents. Especially in the area of passenger transport, such as at aircraft tires, bus tires, or railway wheels monitoring the tires and wheels could bring much more safety.
From Proc. IEEE 1998 MMT/AP International Workshop on Commercial Radio Sensor and Communication Techniques, pages 83 to 96, the use of surface wave sensors for the detection of the deformation of the tires is known. The cause of the deformation, however, such as temperature, internal tire pressure, or outside influences, are not detected herewith. The detected signal may then be transmitted to a vehicle mounted receiver unit in a wireless manner, for example inductively or by radio.
Another solution for the detection of the tire deformation is described in EP 1 186 853 A2. Here, the profile is impressed into the side wall of the rubber product, and the deformation of this profile by influences, such as internal tire pressure or also outside influences, for example by the road conditions, is measured in various ways. Possible principles for the detection of the profile deformation are the capacitive measurement, the optical measurement, measurement by ultra-sound, and also the measurement by eddy current.
Independent of the kind of the implementation of the sensor in the tire, the requirement every system has to meet is the wireless transmission of the measurement data from the wheel or tire to the vehicle. Suitable transmission methods hereof are the inductive transmission, the transmission by means of electromagnetic waves in the infrared region, or also the transmission by radio.
Due to the high weight and rigidity of the housing, the sensors are in most cases currently being mounted near the rim. The current supply, for example by means of batteries, or the assemblies for the wireless data transmission, such as induction coils or antennas, currently also have to be worked into the tire element separate from the sensor itself.